Aerators, useful for aerating aquariums and bait buckets to maintain fish or bait alive, are known in the art. Many types of aerators per se are known, for example, Rowe, U.S. Pat. No. 3,820,272, shows a porous stone through which air is diffused. Howard, U.S. Pat. No. 3,217,444, and Abell, U.S. Pat. No. 2,865,618 describe metal screen diffusers. Coleman, U.S. Pat. No. 1,731,921, Ayers, U.S. Pat. No. 668,899, and Evans, U.S. Pat. No. 299,765, each show perforated elongate pipes for distributing air.
Porous irrigation pipe for distributing water is shown in Turner, U.S. Pat. Nos. 4,003,408, 4,110,420, and 4,168,799. The material of Turner has been proposed for use in aerating sewage sludge.